This invention relates to optical couplers and more particularly to an optical coupler employing optical fibers having dichroic reflectors for selective transmission and reflection of light propagating in the associated fibers.
Optical beam splitters operate to divide an incident beam of light into two beams for application to two additional circuits. A beam splitter is a form of coupling device to enable application of the split beams to various alternate circuits included in different circuit paths. A coupler or beam splitter can be employed as a circuit device in various optical systems to enable a designer to gain increased flexibility in system operation.
For example, wavelength multiplexing is an increasingly important concept in the design of fiber optic systems. Presently, there are sources available for the 0.8 to 0.9 um region of low fiber loss, and other sources and detectors are used in various stages of development for greater than 1.0 um wavelengths. Using the appropriate couplers, these sources can be multiplexed and demultiplexed in a given system in order to increase the information capacity, provide security among different communications channels, or to provide other benefits such as bidirectional transmission over a single fiber.
There is a need to provide an efficient optical coupler to enable this type and other types of operation. The coupler may be employed as a beam splitter or multiplexer element as desired and should preferably be capable of bidirectional transmission, while being rugged, small and reliable.
An example of a particularly useful beam splitter coupler employing dielectric or metal coating on fiber surfaces is described in a copending patent application entitled "Optical Beam Splitter Couplers using Metal or Dielectric Coatings" by Gary W. Bickel Ser. No. 74,923 and assigned to the Assignee herein.
This specification describes a beam splitter coupler employing coatings with dichroic properties evaporated or deposited on an angled fiber face to afford reflection and transmission of a light beam propagated by the optical fiber to enable selective coupling of the beam.